Multivalent meningococcal conjugates and methods for preparing conjugates

ABSTRACT

Disclosed herein are meningococcal immunogenic conjugates which can elicit immune responses against meningococcal polysaccharides (PS) from groups A, C, W-135, and Y and group B factor H binding protein (fHbp). The disclosed conjugates also exhibit bactericidal activity against meningococcal A, C, W-135, Y, B, and X serogroups. Also disclosed are improved methods for preparing conjugates, such as immunogenic conjugates, including activation of a polysaccharide with a cyanylation agent at about 4° C.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the §371 U.S. National Stage of International Application No.PCT/US2013/042428, filed May 23, 2013, which was published in Englishunder PCT Article 21(2), which in turn claims the benefit of U.S.Provisional Application No. 61/651,382, filed May 24, 2012, which isincorporated herein by reference in its entirety.

FIELD

This disclosure relates to conjugates, particularly immunogenicmeningococcal conjugates, and methods of making such conjugates.

BACKGROUND

Among thirteen isolated meningococcal serogroups, A, B, C, W-135, and Yare the most prevalent. There are three FDA-approved capsularpolysaccharide (PS)-based vaccines—Menomune® tetravalent PS vaccine(Sanofi Pasteur), and Menactra® (Sanofi Pasteur) and Menveo® (Novartis)tetravalent conjugate vaccines for protection against meningococcaldisease caused by groups A, C, W-135, and Y Neisseria meningitidis.Group B capsular PS, a polysialic acid with an α2→8 glycosidic linkage,is similar to the PS structure expressed in certain human tissues (Finneet al., Lancet 2:355-357, 1983), thus making it a poor immunogen.Furthermore, if used as a vaccine, the possibility exists of it inducingan autoimmune response. Thus, a need remains to develop additionalmeningococcal vaccines, particularly for group B and group Xmeningococcal serogroups.

SUMMARY

Disclosed herein are immunogenic conjugates including at least onepolysaccharide or protein conjugated to a Neisseria surface protein, forexample group B factor H binding protein (fHbp) or Neisseria surfaceprotein A (NspA). In some examples, the conjugates are meningococcalimmunogenic conjugates which can elicit immune responses againstmeningococcal polysaccharides (PS) from groups A, C, W-135, and Y. Inadditional examples, the immunogenic conjugates can also elicit immuneresponses against fHbp or NspA. In further examples, the disclosedconjugates also exhibit bactericidal activity against meningococcal A,C, W-135, Y, B, and X serogroups. In some examples, the immunogenicconjugates are multivalent immunogenic conjugates.

Also disclosed are improved methods for preparing conjugates, includingsuch immunogenic conjugates. In some embodiments, the methods includereacting at least one first moiety (such as a PS, protein, drug, orother compound) with a cyanylation agent at about 2° C. to about 6° C.,resulting in a cyanate-activated first moiety and contacting thecyanate-activated first moiety with a second moiety (such as a PS,protein, drug, or other compound) having at least one amino group or atleast one hydrazide group (such as a hydrazide-activated second moiety)at about 2° C. to about 6° C., resulting in a conjugate that includes atleast one C—N bond formed between the at least one first moiety and theat least one second moiety.

In some non-limiting embodiments, the methods include reacting at leastone polysaccharide with a cyanylation agent at about 2° C. to about 6°C., resulting in a cyanate-activated polysaccharide and contacting thecyanate-activated polysaccharide with at least one protein (such as fHbpor NspA), resulting in an immunogenic conjugate that includes at leastone C—N bond formed between the at least one polysaccharide and the atleast one protein. In some examples, the methods also include reactingthe at least one protein with hydrazine, carbohydrazide, hydrazinechloride, a dihydrazide, or a mixture thereof at about 2° C. to about 6°C., producing a solution of at least one hydrazide-activated protein andcontacting the at least one cyanate-activated polysaccharide with atleast one protein at about 2° C. to about 6° C., such that the at leastone cyanate-activated polysaccharide reacts with the at least onehydrazide-activated protein, resulting in an immunogenic conjugate thatincludes at least one C—N bond formed between the at least onepolysaccharide and the at least one protein

The foregoing and other features of the disclosure will become moreapparent from the following detailed description, which proceeds withreference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1B are a pair of digital images of purified recombinantmeningococcal factor H binding protein variant 1 (fHbp1), variant 2(fHbp2), and their fusion product (fHbp(1+2)). FIG. 1A is a digitalimage of SDS-PAGE analysis: fHbp1 in lane 1; fHbp2 in lane 2; fHbp(1+2)in lane 3; and the molecular weight ladder in lane 4. FIG. 1B is adigital image of a Western blot analysis using monoclonal antibodies Jar5 (specific to fHbp1) and Jar 11 (specific to fHbp 2). fHbp(1+2) inlanes 1 and 4 was developed with monoclonal antibodies Jar 5 and Jar 11,respectively; fHbp1 in lane 2 was developed with monoclonal antibody Jar5; and fHbp2 in lane 3 was developed with monoclonal antibody Jar 11.

FIG. 2 is a plot of size-exclusion HPLC profiles (monitored at 280 nm)of conjugate products of fHbp(1+2) and meningococcal serogroup Cpolysaccharide (MCPS) prepared under the original conjugation conditions(bottom trace; room temperature) or the modified conjugation conditions(top trace; 4° C.). fHbp(1+2)MCPS conjugate indicates the PS-fHbpconjugate; fHbp(1+2) indicates the unconjugated fHbp protein.

FIGS. 3A and 3B are a set of HPLC profiles of conjugate products. FIG.3A is a set of HPLC profiles of fHbp1 and conjugate products offHbp1MCPS, fHbp2MCPS, and fHbp(1+2)MCPS monitored at 280 nm. The proteinsignals move from low molecular weight elution time (about 23 minutes)to high molecular weight position (about 17.5 minutes) upon conjugation.FIG. 3B is a set of HPLC profiles of fHbp(1+2) and conjugate products offHbp(1+2) and meningococcal serogroup A polysaccharide (MAPS),fHbp(1+2)MCPS, fHbp(1+2) and meningococcal serogroup W-135polysaccharide (MWPS), and fHbp(1+2) and meningococcal serogroup Ypolysaccharide (MYPS) monitored at 280 nm. The protein signals move fromabout 22.5 minutes to about 15.5-18.5 minutes upon conjugation.

SEQUENCE LISTING

Any nucleic acid and amino acid sequences listed herein or in theaccompanying sequence listing are shown using standard letterabbreviations for nucleotide bases and amino acids, as defined in 37C.F.R. §1.822. In at least some cases, only one strand of each nucleicacid sequence is shown, but the complementary strand is understood asincluded by any reference to the displayed strand.

The Sequence Listing is submitted as an ASCII text file in the form ofthe file named Sequence_Listing.txt, which was created on Nov. 20, 2014,and is 18,139 bytes, which is incorporated by reference herein.

SEQ ID NOs: 1 and 2 are exemplary NspA nucleic acid and amino acidsequences, respectively.

SEQ ID NOs: 3 and 4 are exemplary fHbp1 nucleic acid and amino acidsequences, respectively.

SEQ ID NOs: 5 and 6 are exemplary fHbp2 nucleic acid and amino acidsequences, respectively.

SEQ ID NOs: 7 and 8 are exemplary fHbp1-fHbp2 fusion nucleic acid andamino acid sequences, respectively.

SEQ ID NOs: 9 and 10 are the nucleic acid sequences of forward andreverse fHbp1 primers, respectively.

SEQ ID NOs: 11 and 12 are the nucleic acid sequences of forward andreverse fHbp2 primers, respectively.

SEQ ID NOs: 13 and 14 are the nucleic acid sequences of additionalreverse fHbp1 primers.

SEQ ID NOs: 15 and 16 are the nucleic acid sequences of additionalforward fHbp2 primers.

DETAILED DESCRIPTION

Kohn and Wilchek first introduced 1-cyano-4-dimethylaminopyridiniumtetrafluoroborate (CDAP as a substitute for CNBr in the activation ofthe hydroxyl group on PS resins (Appl. Biochem. Biotech. 9:285-305,1984). Designated protein was then mixed with and conjugated to theactivated PS resins for affinity chromatography. This method wassubsequently used to activate soluble PS to prepare PS-proteinconjugates (e.g., Lees et al., Vaccine 26:190-198, 1996). This methodrequired 2-2.5 minutes activation time for PS at pH 9 at roomtemperature in order to achieve optimal yield of conjugate product.

Disclosed herein are conjugation methods which avoid the inconvenientand less controllable procedure of 2-2.5 minutes PS activation time. Itwas found that PS can be activated by CDAP at about 4° C. for 1.5-3hours and achieve better yield of conjugation with protein. Withoutbeing bound by theory, it may be that CDAP and the resulting cyanategroups have longer half-life at lower temperatures (e.g., 4° C.) than atroom temperature. A similar phenomenon was observed for PS conjugatingto hydrazide groups in hydrazide-activated protein at 4° C. Thus, thedisclosed methods provide advantages for production ofpolysaccharide-protein conjugates, including improved control,convenience, and yield. These features may be particularly advantageousfor large-scale production of conjugates, for example, for commercialvaccine production.

The disclosed improved conjugation methods are not limited to productionof conjugates of PS and proteins. These improved methods can be utilizedfor conjugation of any cyanate-activated moiety with any moietyincluding an amino group or any hydrazide-activated moiety, providingimproved convenience and increased yield of the resulting conjugate. Forexample, the disclosed methods can be used to produce chemical,biochemical, medical, pharmacological, diagnostic and/or therapeuticreagents.

I. Abbreviations

ADH adipic acid dihydrazide

APDO 1-amino-2,3-propanediol

CAPS 3-(cyclohexylamino)-1-propanesulfonicacid

CDAP 1-cyano-4-dimethylaminopyridinium tetrafluoroborate

CHES (2-(N-cyclohexylamino)ethane sulfonic acid

EDC 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride

fHbp factor H binding protein

fHbp1 factor H binding protein 1 (subfamily B)

fHbp2 factor H binding protein 2 (subfamily A)

HEPES N-(2-Hydroxyethyl) piperazine-N′-(2-ethanesulfonic acid)

MAPS meningococcal serogroup A polysaccharide

MCPS meningococcal serogroup C polysaccharide

MWPS meningococcal serogroup W-135 polysaccharide

MYPS meningococcal serogroup Y polysaccharide

NspA Neisseria surface protein A

PS polysaccharide

TT tetanus toxoid

II. Terms

Unless otherwise explained, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this disclosure belongs. The singular terms“a,” “an,” and “the” include plural referents unless the context clearlyindicates otherwise. Similarly, the word “or” is intended to include“and” unless the context clearly indicates otherwise. It is further tobe understood that all base sizes or amino acid sizes, and all molecularweight or molecular mass values, given for nucleic acids or polypeptidesare approximate, and are provided for description. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of this disclosure, suitable methods andmaterials are described below. The term “comprises” means “includes.”All publications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety for allpurposes. All GenBank Accession Nos. mentioned herein are incorporatedby reference in their entirety as of May 24, 2012. In case of conflict,the present specification, including explanations of terms, willcontrol. In addition, the materials, methods, and examples areillustrative only and not intended to be limiting.

Unless otherwise noted, technical terms are used according toconventional usage. Definitions of common terms in molecular biology maybe found in Benjamin Lewin, Genes V, published by Oxford UniversityPress, 1994 (ISBN 0-19-854287-9); Kendrew et al. (eds.), TheEncyclopedia of Molecular Biology, published by Blackwell Science Ltd.,1994 (ISBN 0-632-02182-9); and Robert A. Meyers (ed.), Molecular Biologyand Biotechnology: a Comprehensive Desk Reference, published by VCHPublishers, Inc., 1995 (ISBN 1-56081-569-8).

In order to facilitate review of the various embodiments of thedisclosure, the following explanations of specific terms are provided:

Adjuvant: A substance or vehicle that non-specifically enhances theimmune response to an antigen. Adjuvants can include a suspension ofminerals (such as alum, aluminum hydroxide, or phosphate) on whichantigen is adsorbed or water-in-oil emulsion in which antigen solutionis emulsified in mineral oil (for example, Freund's incompleteadjuvant), sometimes with the inclusion of killed mycobacteria (Freund'scomplete adjuvant) to further enhance antigenicity. Immunostimulatoryoligonucleotides (such as those including a CpG motif) can also be usedas adjuvants (for example, see U.S. Pat. Nos. 6,194,388; 6,207,646;6,214,806; 6,218,371; 6,239,116; 6,339,068; 6,406,705; and 6,429,199).Adjuvants also include biological molecules, such as costimulatorymolecules. Exemplary biological adjuvants include IL-2, RANTES, GM-CSF,TNF-α, IFN-γ, G-CSF, LFA-3, CD72, B7-1, B7-2, OX-40L and 41 BBL.

Antigen: A compound, composition, or substance that may be specificallybound by the products of specific humoral or cellular immunity, such asan antibody molecule or T-cell receptor. Antigens can be any type ofbiologic molecule including, for example, simple intermediarymetabolites, sugars (e.g., oligosaccharides), lipids, and hormones aswell as macromolecules such as complex carbohydrates (e.g.,polysaccharides), phospholipids, nucleic acids and proteins. Categoriesof antigens include, but are not limited to, viral antigens, bacterialantigens, fungal antigens, protozoa and other parasitic antigens, tumorantigens, antigens involved in autoimmune disease, allergy and graftrejection, toxins, and other miscellaneous antigens.

Carrier: An immunogenic molecule to which a hapten or an antigen (suchas a polysaccharide), can be bound or conjugated. When bound orconjugated to a carrier, the molecule may become more immunogenic.Carriers are chosen to increase the immunogenicity of the bound orconjugated molecule and/or to elicit antibodies against the carrierwhich are diagnostically, analytically, and/or therapeuticallybeneficial. Covalent linking of a molecule to a carrier can conferenhanced immunogenicity and T-cell dependence (Pozsgay et al., PNAS96:5194-97, 1999; Lee et al., J. Immunol. 116:1711-18, 1976; Dintzis etal., PNAS 73:3671-75, 1976). Useful carriers include polymeric carriers,which can be natural (for example, proteins from bacteria or viruses),semi-synthetic, or synthetic materials containing one or more functionalgroups to which a reactant moiety can be attached.

Examples of bacterial products for use as carriers include bacterialtoxins, such as B. anthracis protective antigen (including fragmentsthat contain at least one antigenic epitope and analogs or derivativescapable of eliciting an immune response), lethal factor and lethaltoxin, and other bacterial toxins and toxoids, such as tetanustoxin/toxoid, diphtheria toxin/toxoid, P. aeruginosa exotoxin/toxoid,pertussis toxin/toxoid, and C. perfringens exotoxin/toxoid. As disclosedherein, meningococcal factor H binding proteins or NspA proteins arealso useful carrier proteins. Viral proteins, such as hepatitis Bsurface antigen and core antigen can also be used as carriers.

Conjugate (conjugating): Coupling a first unit to a second unit. Thisincludes, but is not limited to, covalently bonding one molecule toanother molecule (for example, directly or via a linker molecule),noncovalently bonding one molecule to another (e.g. electrostaticallybonding) (see, for example, U.S. Pat. No. 6,921,496, which disclosesmethods for electrostatic conjugation), non-covalently bonding onemolecule to another molecule by hydrogen bonding, non-covalently bondingone molecule to another molecule by van der Waals forces, and any andall combinations of such couplings. In one embodiment, conjugatingincludes covalent bond linkage of a polysaccharide to a protein. Thecovalent bond linkage can be direct or indirect, e.g., linked though aspacer molecule.

Covalent bond: An interatomic bond between two atoms, characterized bythe sharing of one or more pairs of electrons by the atoms. The terms“covalently bound” or “covalently linked” refer to making two separatemolecules into one contiguous molecule.

Effective amount: A quantity of a specified agent sufficient to achievea desired effect in a subject being treated with that agent. Forexample, this may be the amount of an immunogenic conjugate (such as ameningococcal PS-fHbp conjugate) useful in increasing resistance to,preventing, ameliorating, and/or treating infection and disease causedby a bacterial infection in a subject. A therapeutically effectiveamount of an agent may include an amount sufficient to increaseresistance to, prevent, ameliorate, and/or treat infection and diseasecaused by infection in a subject without causing a substantial cytotoxiceffect in the subject. The effective amount or therapeutically effectiveamount of an agent useful for increasing resistance to, preventing,ameliorating, and/or treating infection and disease caused by infectionin a subject will be dependent on the subject being treated, theseverity of the affliction, and the manner of administration of thecomposition.

Factor H binding protein (fHbp): A meningococcal surface protein, alsoknown as GNA1870 or LP2086 (Masignani et al., J. Exp. Med. 197:789-799,2003; Fletcher et al., Inf. Immun. 72:2088-2100, 2004). fHbp binds tofactor H, which is a cofactor in the cleavage of C3b to iC3b, preventsassociation of factor B with C3b slowing formation of the alternativepathway C3 convertase, and irreversibly dissociates the C3 convertaseonce it is formed. There are two subfamilies of fHbp, subfamily A (alsoreferred to as fHbp2) and subfamily B (also referred to as fHbp1). ThefHbp proteins exhibit substantial sequence variation among N.meningitidis strains, but all bind to factor H.

fHbp nucleic acid and protein sequences are publicly available.Exemplary fHbp nucleic acid sequences include GenBank Accession Nos.NC_003112 (1975218-1976180), AY330353, AY330354, AY330363, AY330361,AY330367, AY330370, AY330375, AY330398, AY330399, AY330400, AY330401,AY330406, AY330407, AY330408, AY330409, AY330411, JN580522, and theassociated amino acid sequences, all of which are incorporated herein byreference as present in GenBank on May 24, 2012. One of skill in the artcan identify additional fHbp nucleic acid and protein sequences.

Immune response: A response of a cell of the immune system, such as aB-cell, T-cell, macrophage or polymorphonucleocyte, to a stimulus. Animmune response can include any cell of the body involved in a hostdefense response for example, an epithelial cell that secretesinterferon or a cytokine. An immune response includes, but is notlimited to, an innate immune response or inflammation.

Immunogen: A compound, composition, or substance which is capable, underappropriate conditions, of stimulating the production of antibodies or aT-cell response in a subject, including compositions that are injectedor absorbed into a subject.

Immunogenic conjugate or composition: A composition useful forstimulating or eliciting a specific immune response (or immunogenicresponse) in a subject. In some embodiments, the immunogenic response isprotective or provides protective immunity, in that it enables thesubject to better resist infection or disease progression from theorganism against which the immunogenic composition is directed. Onespecific example of a type of immunogenic composition is a vaccine.

Immunogenic-distinct polysaccharide: A polysaccharide that elicits animmune response that differs from the immune response elicited byanother type of polysaccharide. Immunogenic-distinct polysaccharides maybe two or more polysaccharides from different encapsulated bacteria. Forexample, a pneumococcal polysaccharide is an immunogenic-distinctpolysaccharide compared to a meningococcal polysaccharide.Immunogenic-distinct polysaccharides also are inclusive of two or morepolysaccharides from different serogroups or serotypes. For example, ameningococcal polysaccharide of serogroup A is an immunogenic-distinctpolysaccharide compared to a meningococcal polysaccharide of serogroupC.

Inhibiting or treating a disease: “Inhibiting” a disease refers toinhibiting the full development of a disease or condition, for example,in a subject who is at risk for a disease such as meningococcalmeningitis. Inhibition of a disease can span the spectrum from partialinhibition to substantially complete inhibition (prevention) of thedisease. In some examples, the term “inhibiting” refers to reducing ordelaying the onset or progression of a disease. “Treatment” refers to atherapeutic intervention that ameliorates a sign or symptom of a diseaseor pathological condition after it has begun to develop. As used herein,the term “ameliorating,” with reference to a disease, pathologicalcondition or symptom, refers to any observable beneficial effect of thetreatment. The beneficial effect can be evidenced, for example, by adelayed onset of clinical symptoms of the disease in a susceptiblesubject, a reduction in severity of some or all clinical symptoms of thedisease, a slower progression of the disease, a reduction in the numberof relapses of the disease, an improvement in the overall health orwell-being of the subject, or by other parameters well known in the artthat are specific to the particular disease.

Multivalent immunogenic conjugate or multivalent conjugate vaccine: Amolecule or conjugate including more than one antigenic epitope. Onetype of a multivalent immunogenic conjugate includes a mixture ofdifferent molecules, each molecule comprising differentimmunogenic-distinct polysaccharides wherein each differentimmunogenic-distinct polysaccharide is conjugated to a separate proteincarrier (which may be the same or different protein carriers). Anothertype of a multivalent immunogenic conjugate is a molecule in which aplurality of immunogenic-distinct polysaccharides are conjugated to asingle protein molecule or single protein construct (which proteinconstruct itself includes more than one different protein). A furthertype of multivalent immunogenic conjugate includes a mixture of theconjugates of the first type and the conjugates of the second type. Anexample of the first type of multivalent immunogenic conjugate may bedepicted as a mixture of the different structures represented by:

-   -   P¹-PS¹; P¹-PS²; and P¹-PS³    -   wherein P¹ is a carrier protein; and PS¹, PS², and PS³ are each        immunogenic-distinct polysaccharides.        An example of the second type of multivalent immunogenic        conjugate may be depicted as a structure represented by:

-   -   wherein P¹ is a carrier protein; PS¹, PS², and PS³ are each        immunogenic-distinct polysaccharides that are covalently        attached to P¹.

The protein and polysaccharide in the above formulae can be singular orplural structural units, and there is at least one bond formed betweenthe protein and the polysaccharide.

Neisseria meningitidis: A bacterium which causes meningococcalmeningitis in humans. There are at least thirteen serogroups of N.meningitis, including groups A, B, C, W-135, X, Y, D, 29E, H, I, K, L,and Z, which are classified based on the composition of theirpolysaccharide capsule. Of these, A, B, C, W-135, X, and Y account forthe majority of meningococcal disease. Symptoms of meningococcalmeningitis include stiff neck, high fever, light sensitivity, headaches,and vomiting. Even with early diagnosis and antibiotic treatment, 5-10%of infected individuals die. Meningococcal meningitis may also result inbrain damage or hearing loss in 10-20% of those who survive the disease.Meningococcal disease may also progress to meningococcal septicemia,characterized by hemorrhagic rash and rapid circulatory collapse.

N. meningitidis bacteria are spread through contact with respiratory orthroat secretions of carriers (such as through coughing, sneezing,kissing, sharing food or utensils, and living in close proximity). Up to10-20% of the population may carry the bacteria in the nasopharynxwithout symptoms at any given time and the carriage rate may be evenhigher during an epidemic.

Neisserial surface protein A (NspA): A meningococcal surface proteincapable of binding to factor H (Lewis et al., PloS Pathogens6:e1001027).

NspA nucleic acid and protein sequences are publicly available.Exemplary NspA nucleic acid sequences include GenBank Accession Nos.NC_003112.2 (690298 . . . 690822, complement), NC_013016.1 (590409 . . .590933, complement), NC_010120.1 (632166 . . . 632690, complement), andNC_008767.1 (635025 . . . 635549, complement) and their associated aminoacid sequences, all of which are incorporated by reference as present inGenBank on May 24, 2012. One of skill in the art can identify additionalNspA sequences.

Pharmaceutically acceptable carrier: The pharmaceutically acceptablecarriers (vehicles) useful in this disclosure are conventional.Remington: The Science and Practice of Pharmacy, The University of theSciences in Philadelphia, Editor, Lippincott, Williams, & Wilkins,Philadelphia, Pa., 21^(st) Edition (2005), describes compositions andformulations suitable for pharmaceutical delivery of one or moretherapeutic compounds or molecules, such as one or more disclosedimmunogenic conjugates, and additional pharmaceutical agents.

Subject: Living multi-cellular vertebrate organisms, a category thatincludes both human and non-human mammals. Subjects include veterinarysubjects, including livestock such as cows and sheep, rodents (such asmice and rats), and non-human primates.

III. Immunogenic Conjugates

Disclosed herein are novel immunogenic conjugates which include apolysaccharide (such as one or more bacterial polysaccharides) or aprotein (such as a bacterial surface protein or an immunogenic portionthereof) conjugated to a carrier protein, for example, a Neisseriasurface protein, such as meningococcal fHbp or NspA. The disclosedconjugates are immunogenic in a subject (as demonstrated in theExamples, below).

In particular non-limiting embodiments, the disclosed immunogenicconjugates include one or more (such as 1, 2, 3, 4, or more)immunogenic-distinct polysaccharides conjugated to fHbp or NspA. Inparticular examples, the immunogenic conjugates include one or moremeningococcal polysaccharides (such as one or more meningococcalserogroups A, C, W-135, Y, or X polysaccharides) conjugated to fHbp orNspA. In other examples, the immunogenic conjugates include one or morepneumococcal, group B streptococcal, Haemophilus influenzae type b, orSalmonella typhi polysaccharides conjugated to fHbp or NspA.

In other embodiments, the disclosed immunogenic conjugates include oneor more (such as 1, 2, 3, 4, or more) proteins or an immunogenic portionthereof conjugated to a carrier protein, such as fHbp or NspA. In someexamples, the immunogenic conjugates include one or more bacterialsurface proteins conjugated to fHbp. In other examples, the immunogenicconjugates include one or more bacterial surface proteins conjugated toNspA.

In some embodiments, the immunogenic conjugates are multivalentimmunogenic conjugates, such as a conjugate including more than oneantigenic epitope. In some examples, a multivalent immunogenic conjugateincludes a mixture of different molecules, each molecule includingdifferent immunogenic-distinct polysaccharides wherein each differentimmunogenic-distinct polysaccharide is conjugated to a separate proteincarrier (each of which may be the same or different protein carriers).In one non-limiting example, such a multivalent immunogenic conjugatemay be depicted as a mixture of the different structures represented by:

-   -   P¹-PS¹; P¹-PS²; and P¹-PS³ or    -   P²-PS¹; P²-PS²; and P²-PS³,        wherein P¹ and P² are carrier proteins (for example fHbp and        NspA); and PS¹, PS², and PS³ are each immunogenic-distinct        polysaccharides.

In other examples, a multivalent immunogenic conjugate includesmolecules in which a plurality of immunogenic-distinct polysaccharidesare conjugated to a single protein molecule or single protein construct(which protein construct itself includes more than one differentprotein). A non-limiting example of such a multivalent conjugate may bedepicted as a structure represented by:

wherein P¹ and P² are carrier proteins (such as fHbp and NspA); PS¹,PS², and PS³ are each immunogenic-distinct polysaccharides that arecovalently attached to P¹ or P².

In yet another example, a multivalent immunogenic conjugate includes amixture of one or more of the conjugates described above. In oneexample, a multivalent immunogenic conjugate includes a mixture ofconjugates of MAPS-fHbp, MCPS-fHbp, MWPS-fHbp, and MYPS-fHbp. In anotherexample, a multivalent immunogenic conjugate can also include a mixtureof one or more immunogenic conjugates of a polysaccharide conjugated tofHbp and one or more immunogenic conjugates of a polysaccharideconjugated to NspA.

A. Polysaccharides

The term “polysaccharide” as used herein, is a broad term and is used inits ordinary sense, including, without limitation, saccharidescomprising a plurality of repeating units, including, but not limited topolysaccharides having 50 or more repeat units, and oligosaccharideshaving 50 or less repeating units. Typically, polysaccharides have fromabout 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 repeating units to about2,000 or more repeating units, and such as from about 100, 150, 200,250, 300, 350, 400, 500, 600, 700, 800, 900 or 1000 repeating units toabout, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, or 1900 repeatingunits. Oligosaccharides typically have from about 6, 7, 8, 9, or 10repeating units to about 15, 20, 25, 30, or 35 to about 40 or 45repeating units.

In some examples, polysaccharides for use in the disclosed conjugatesand methods include polysaccharides and oligosaccharides fromencapsulated bacteria. The polysaccharides and oligosaccharides can befrom any source, for example, they can be derived fromnaturally-occurring bacteria, genetically engineered bacteria, or can beproduced synthetically. The polysaccharides and oligosaccharides can besubjected to one or more processing steps prior to activation, forexample, purification, functionalization, depolymerization using mildoxidative conditions, deacetylation, and the like. Post processing stepscan also be employed, if desired. Any suitable method known in the artfor synthesizing, preparing, and/or purifying suitable polysaccharidesand oligosaccharides can be employed.

Polysaccharides and oligosaccharides for use in the disclosed conjugatesand methods include pneumococcal polysaccharides of, for example,serogroups 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B,17F, 18C, 19A, 19F, 20, 22F, 23F and 33F; meningococcal polysaccharidesof serotypes A, B, C, W-135, and Y, Haemophilus influenzae type bpolysaccharide polyribosylribitol phosphate, group B streptococcalpolysaccharides of serotypes III and V, and Salmonella typhi Vipolysaccharide. Other polysaccharides of pneumococcal and group Bstreptococcal serotypes, and meningococcal serogroups are also suitablefor use herein, as are other T-independent polysaccharide andoligosaccharide antigens, for example, polysaccharides oroligosaccharides derived from group A streptococcus, Staphylococci,Enterococci, Klebsiella pneumoniae, E. coli, Pseudomonas aeruginosa, andBacillus anthracis. While bacterial polysaccharides and oligosaccharidesare particularly suitable, gram-negative bacterial lipopolysaccharidesand lipooligosaccharides and their polysaccharide and oligosaccharidederivatives, and viral polysaccharides and oligosaccharides can also beemployed. In one example, detoxified mutant meningococcallipooligosaccharides can be used in the disclosed conjugates (see, e.g.,Weynants et al., Inf. Immun. 77:2084-2093, 2009).

Polysaccharides with side chain phosphorus and/or backbone phosphorusare suitable for use in the disclosed conjugates and methods. Theconjugation reactions (such as those described in Section IV, below) areparticularly well suited for use with polysaccharides having phosphorusin the backbone, although they are not limited to such polysaccharides.

B. Carrier Proteins

In some embodiments, the disclosed immunogenic conjugates include apolysaccharide or at least a portion of (such as an immunogenic portionof) one or more (such as 1, 2, 3, 4, or more) proteins (such as one ormore bacterial surface proteins) conjugated to a carrier protein. Insome examples, the carrier protein is a Neisseria surface protein. Inparticular embodiments, the carrier protein is fHbp. In some examples,the immunogenic conjugate includes a meningococcal polysaccharide orprotein conjugated to fHbp. In other embodiments, the carrier protein isNspA. In some examples, the immunogenic conjugate includes ameningococcal polysaccharide or protein conjugated to NspA. In otherexamples, the immunogenic conjugate includes meningococcal outermembrane vesicles or meningococcal outer membrane protein mixtureconjugated to fHbp or NspA.

Nucleic acid and amino acid sequences of NspA are publicly available. Insome examples, an NspA protein is encoded by a nucleic acid sequence atleast 70% (such as at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%,or even 100%) identical to the nucleic acid sequence set forth as SEQ IDNO: 1. In some examples, an NspA protein is at least 70% (such as atleast 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or even 100%)identical to the amino acid sequence set forth as SEQ ID NO: 2.

Factor H binding protein (fHbp) is a meningococcal surface protein, alsoknown as GNA1870 or LP2086 (Masignani et al., J. Exp. Med. 197:789-799,2003; Fletcher et al., Inf. Immun. 72:2088-2100, 2004). fHbp binds tofactor H, which is a cofactor in the cleavage of C3b to iC3b, preventsassociation of factor B with C3b slowing formation of the alternativepathway C3 convertase, and irreversibly dissociates the C3 convertaseonce it is formed. There are two subfamilies of fHbp, subfamily A (alsoreferred to as fHbp2) and subfamily B (also referred to as fHbp1).

Nucleic acid and amino acid sequences of fHbp1 are publicly available.In some examples, an fHbp1 protein is encoded by a nucleic acid sequenceat least 70% (such as at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99%, or even 100%) identical to the nucleic acid sequence set forth asSEQ ID NO: 3. In some examples, an fHbp1 protein is at least 70% (suchas at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or even 100%)identical to the amino acid sequence set forth as SEQ ID NO: 4.

Nucleic acid and amino acid sequences of fHbp2 are publicly available.In some examples, an fHbp2 protein is encoded by a nucleic acid sequenceat least 70% (such as at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99%, or even 100%) identical to the nucleic acid sequence set forth asSEQ ID NO: 5. In some examples, an fHbp2 protein is at least 70% (suchas at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or even 100%)identical to the amino acid sequence set forth as SEQ ID NO: 6.

In some examples, the immunogenic conjugates include a fusion proteinincluding at least a portion of each of fHbp1 and fHbp2. In one example,an fHbp1-fHbp2 fusion protein is encoded by a nucleic acid encodingfHbp1 (or a portion thereof), which is directly or indirectly (forexample via a linker) linked to a nucleic acid encoding fHbp2 (or aportion thereof). In some examples, an fHbp1-fHbp2 fusion protein isencoded by a nucleic acid sequence at least 70% (such as at least 75%,80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or even 100%) identical to thenucleic acid sequence set forth as SEQ ID NO: 7. In some examples, anfHbp-1fHbp2 fusion protein is at least 70% (such as at least 75%, 80%,85%, 90%, 95%, 96%, 97%, 98%, 99%, or even 100%) identical to the aminoacid sequence set forth as SEQ ID NO: 8.

IV. Methods of Preparing Immunogenic Conjugates

The disclosed immunogenic conjugates can be prepared by methodsincluding reductive amination conjugation or cyanylation conjugation. Insome examples, the methods for preparing the immunogenic conjugates arestandard methods known to one of skill in the art. In other examples,the methods are improved methods that provide, for example, increasedconvenience, improved ability to perform large scale reactions, andincreased yield over standard methods. The improved methods can beutilized to prepare a conjugate between any cyanate-activated moiety(such as a PS, protein, drug, or other compound) and any moiety (such asa PS, protein, drug, or other compound) with at least one amino group orany hydrazide-activated moiety (such as a PS, protein, drug, or othercompound). One of skill in the art will recognize that the improvedmethods are not limited to production of immunogenic conjugates, such asthose disclosed herein.

A. Reductive Amination Conjugation

In some embodiments, methods of preparing the disclosed immunogenicconjugates include reductive amination reaction to conjugate apolysaccharide containing aldehyde groups to a protein (such ashydrazide modified protein). In some examples, the methods includereacting at least one polysaccharide with an oxidizing agent, resultingin at least one aldehyde-activated polysaccharide; reacting at least oneprotein with hydrazine, carbohydrazide, hydrazine chloride, adihydrazide, or a mixture thereof, resulting in at least onehydrazide-activated protein; and contacting the at least onealdehyde-activated polysaccharide with the at least onehydrazide-activated protein, resulting in a conjugate with one or moreC═N double bonds between at least one polysaccharide and at least oneprotein. In some examples, the methods further include reducingsubstantially all of the C═N double bonds of the conjugate to C—N bonds(for example with sodium borohydride). Exemplary methods include thosein International Patent Publication Nos. WO 2005/014037, WO 2005/037320,and WO 2007/109129, all of which are incorporated herein by reference intheir entirety. In some examples, the disclosed methods includeconjugating at least one aldehyde-activated meningococcal PS (such asMAPS, MCPS, MWPS, MYPS, or a combination of two or more thereof) to ahydrazide-activated fHbp.

Any suitable functionalization reaction can be employed to activate thepolysaccharide or oligosaccharide with aldehyde groups. Certainpolysaccharides and oligosaccharides possess terminal aldehyde groupsthat can participate in the conjugation reaction. If the polysaccharideor oligosaccharide is activated with aldehyde groups, a preferredreaction involves reaction with an oxidizing agent, such as NaIO₄.Oxidizing agents have the potential for fragmenting the polysaccharideor oligosaccharide. Undesirable fragmentation can be avoided orcontrolled through selection of the particular oxidizing agent and theconcentration of the oxidizing agent employed. Ketone groups are alsocapable of reacting with hydrazide, so activation of the polysaccharideor oligosaccharide with ketone groups can be employed in certainembodiments. In some examples, polysaccharide is reacted with sodiumperiodate at about 2-6° C. (for example, about 2° C., about 2.5° C.,about 3° C., about 3.5° C., about 4° C., about 4.5° C., about 5° C.,about 5.5° C., or about 6° C.) for 6-24 hours (for example about 6,about 7, about 8, about 9, about 10, about 11, about 12, about 13, about14, about 15, about 16, about 17, about 18, about 19, about 20, about21, about 22, about 23, or about 24 hours) or overnight. The activatedpolysaccharide can be purified, for example by diafiltration againstwater.

In some examples, a strongly buffered (e.g., at pH of from about 6.5 toabout 8, with a high buffer concentration of from about 100 mM to about200 mM) activated polysaccharide solution is employed in the conjugationreaction in the form of a strongly buffered solution. Any suitablebuffer can be employed, such as a buffer such as N-(2-Hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid) (HEPES) or phosphate bufferedsaline. In other examples, the activated polysaccharide is bufferexchanged with 10 mM HEPES, pH 7.5.

In some examples, the methods include introducing at least one hydrazidegroup onto the protein (for example, a carrier protein, such as a fHbpor NspA) by reacting the protein with excess hydrazine, carbohydrazide,hydrazine chloride, or a dihydrazide (for example, succinyl dihydrazideor adipic acid dihydrazide (ADH)) catalyzed by a carbodiimide (such as1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDC),although any water-soluble carbodiimide can be used). In some examples,the protein is reacted with hydrazine or ADH in the presence of EDC atabout pH 5.5-6.5 (such as pH about 5.5, about 5.6, about 5.7, about 5.8,about 5.9, about 6.0, about 6.1, about 6.2, about 6.3, about 6.4, orabout 6.5).

In some examples, the hydrazide-activated protein is maintained solubleat a pH of from about 10 to about 11.5, such as from about 10.1, 10.2,10.3, or 10.4 to about 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3,or 11.4, for example about 10.5, with a buffer at a concentration offrom about 3 or less to about 10 mM or more, such as from about 4 or 5mM to about 6, 7, 8, or 9; mM, before conjugation. Suitable buffersinclude but are not limited to Na₂CO₃,3-(cyclohexylamino)-1-propanesulfonic acid (CAPS), and(2-(N-cyclohexylamino)ethane sulfonic acid (CHES). In one example, thehydrazide-activated protein is buffer-exchanged to a solution of aboutpH 10.5 (such as 30 mM NaCl and 3 mM Na₂CO₃, pH 10.5). In otherexamples, the hydrazide-activated protein is maintained soluble atneutral or approximately neutral pH (e.g., pH of about 7 to about 7.5)by activating the protein in the presence of at least one amino acid(such as lysine, arginine, histidine, glycine, serine, threonine,glutamic acid, cysteine, or a mixture of two or more thereof) (see,e.g., WO 07/109129, incorporated herein by reference). Amino acids maybe included in the activation reaction at a concentration of about 1-500mM, about 20-300 mM, or about 36-144 mM.

The hydrazide-based conjugation reaction can be carried to completionwithin one to three days at reactant concentrations of from about 1 toabout 40 mg/mL, or about 1 to about 50 mg/mL, at PS/protein weightratios of from about 1:5 to about 5:1, such as from about 1:2 to about2:1, for example, about 1:1, although in certain embodiments higher orlower ratios can be utilized. In some examples, the conjugation reactionis conducted at temperatures of from about 4° C. to about 40° C., forexample from about 4, 10, 15, or 20° C. to about 25, 30, or 35° C., andat a pH of from about 6 to about 8.5, such as from about 6.1, 6.2, 6.3,6.4, or 6.5 to about 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5,7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, or 8.4, with optimal conditionsvarying according to the polysaccharide.

In conventional reductive amination, the reaction between aldehyde andamino groups is reversible and unfavorable, such that sodiumcyanoborohydride is needed to facilitate the conjugation by convertingthe C═N double bond to a C—N single bond to render the entire reductiveamination event irreversible. In contrast, the reductive aminationconjugation reaction of the disclosed methods proceeds without the aidof sodium cyanoborohydride because of the high efficiency of thehydrazide-aldehyde reaction. At the end of the reductive aminationconjugation reaction, sodium borohydride or another suitable reductantis employed to reduce the C═N double bond to a C—N single bond, as wellas to reduce any residual aldehyde groups to alcohol groups. Thereductive amination conjugation reaction of these methods avoidscontamination of the resulting conjugate with cyanide, a by-product ofsodium cyanoborohydride.

To reduce precipitation of activated protein during the conjugationreaction, the activated protein is provided in the form of a weaklybuffered solution with a low buffer concentration of from about 3 mM toabout 10 mM, which is added to a strongly buffered (at pH of from about6.5 to about 7.5, with a high buffer concentration of from about 100 mMto about 200 mM) activated polysaccharide solution. In particularexamples, the pH of the activated protein solution is buffered to fromabout pH 10 to about pH 11.5, for example, about pH 10.5. The activatedpolysaccharide solution is strongly buffered to from about pH 6 to aboutpH8, such as from about pH 6.5 to about pH 7.5. The hydrazide-aldehydereductive amination reaction proceeds at a fast rate, and theprecipitating effect of a pH lower than 10.5 (for example, a pH as lowas from about 8.5 to about 9.5) on activated protein is overcome by themolecular properties of the reacting activated polysaccharide.

In another embodiment, the disclosed methods include reacting at leastone aldehyde-activated protein with at least one hydrazide-activatedpolysaccharide to produce an immunogenic conjugate. Any suitablefunctionalization reaction can be employed to activate the protein withaldehyde groups. In one example, the protein is reacted with1-amino-2,3-propanediol (APDO) in the presence of EDC. Amino sugars suchas glucosamine, galactosamine, and the like can be used in place ofAPDO. In one example, the methods include reacting at least one proteinwith APDO in the presence of EDC at a pH of from about 6 to about 7,whereby a solution of a APDO-modified protein is obtained; bufferexchanging the solution of the APDO-modified protein to a pH of fromabout 10.0 to about 11.0; reacting the APDO-modified protein with anoxidizing agent, whereby a solution of an aldehyde-activated protein isobtained; buffer exchanging the solution of the aldehyde-activatedprotein to a pH of from about 10.0 to about 11.0; reacting ahydrazide-activated polysaccharide with the aldehyde-activated proteinat a pH of from about 6 to about 8, whereby a conjugate comprising oneor more C═N double bonds is obtained; and reducing substantially all ofthe C═N double bonds of the conjugate to C—N single bonds. In someexamples, the hydrazide-activated polysaccharide is obtained by reactinga polysaccharide with an oxidizing agent (for example, NaIO₄) in asolution, producing an aldehyde-activated polysaccharide; reacting thealdehyde-activated polysaccharide with ADH to produce an intermediateincluding one or more C═N double bonds; and reducing substantially allof the C═N double bonds of the intermediate to C—N single bonds (forexample with NaBH₄), producing a hydrazide-activated polysaccharide.

B. Cyanylation Conjugation

In other embodiments, methods of preparing conjugates (such as thedisclosed immunogenic conjugates) include a cyanylation conjugationreaction to conjugate a moiety containing at least one cyanate group toa moiety including at least one amino group or to at least onehydrazide-activated moiety. In some examples, the methods includeconjugating a polysaccharide containing cyanate groups to a protein(such as a native protein or a hydrazide modified protein). In someembodiments, the improved cyanylation conjugation methods disclosedherein include reacting at least one first moiety (such as a PS,protein, drug, or other compound) with a cyanylation agent at about 2°C. to about 6° C., resulting in a cyanate-activated first moiety andcontacting the cyanate-activated first moiety with a second moiety (suchas a PS, protein, drug, or other compound) having at least one aminogroup or at least one hydrazide group (such as a hydrazide-activatedsecond moiety) at about 2° C. to about 6° C., resulting in a conjugatethat includes at least one C—N bond formed between the at least onefirst moiety and the at least one second moiety. The resultingconjugates are useful for a variety of purposes, including asimmunogenic, diagnostic, and/or therapeutic compounds or reagents. Oneof skill in the art can select appropriate moieties for conjugation bythe cyanylation conjugation methods provided herein, and the methods arenot limited to production of the specific examples provided herein.

In some examples, the disclosed methods include reacting at least onepolysaccharide with a cyanylation agent, resulting in at least onecyanate-activated polysaccharide. In some embodiments, the at least onecyanate-activated polysaccharide is reacted with at least one protein,resulting in a conjugate that includes at least one C—N bond formedbetween at least one polysaccharide and at least one protein. In otherembodiments, the at least one cyanate-activated polysaccharide isreacted with a hydrazide-activated protein. Thus, in some examples, themethods also include reacting at least one protein with hydrazine,carbohydrazide, hydrazine chloride, a dihydrazide or a mixture thereof,resulting in at least one hydrazide-activated protein. Exemplary methodsinclude those in International Patent Publication Nos. WO 2005/014037,WO 2005/037320, and WO 2007/109129, all of which are incorporated hereinby reference in their entirety. In some examples, the disclosed methodsinclude conjugating at least one cyanate-activated meningococcal PS(such as MAPS, MCPS, MWPS, MYPS, or a combination of two or morethereof) to a fHbp protein (such as a native fHbp or ahydrazide-activated fHbp). In other examples, the disclosed methodsinclude conjugating at least one cyanate-activated meningococcal PS(such as MAPS, MCPS, MWPS, MYPS, or a combination of two or morethereof) to a NspA protein.

Any suitable functionalization reaction can be employed to activate thepolysaccharide or oligosaccharide with cyanate groups. In onenon-limiting example, the polysaccharide or oligosaccharide is reactedwith 1-cyano-4-dimethylammoniumpyridinium tetrafluoroborate (CDAP) inthe presence of triethylamine. Additional cyanylation agents includecyanogen bromide, p-nitrophenyl cyanate (pNPC),1-cyano-4-pyrrolidiniopyridinium tetrafluoroborate (CPIP), andN-cyano-N,N,N-triethylammonium tetrafluoroborate (CTEA).

In some examples, at least one polysaccharide is reacted with acyanylation agent (for example CDAP) at about 20° C.-25° C. (such asabout 20° C., about 21° C., about 22° C., about 23° C., about 24° C., orabout 25° C.) in the presence of triethylamine for about 1-5 minutes(such as about 1, about 1.5, about 2, about 2.5, about 3, about 3.5,about 4, about 4.5, or about 5 minutes). In other examples, at least onepolysaccharide is reacted with a cyanylation agent (such as CDAP) atabout 2° C.-6° C. (such as about 2° C., about 2.5° C., about 3° C.,about 3.5° C., about 4° C., about 4.5° C., about 5° C., about 5.5° C.,or about 6° C., for example about 4° C.) in the presence oftriethylamine for about 1-3 hours (for example about 1, about 1.5, about2, about 2.5, or about 3 hours).

Activation of polysaccharide with a cyanylation agent (such as CDAP) atabout 4° C. for longer times is more convenient and easier to controlthan the conventional activation for short periods of time at roomtemperature. In particular, a longer reaction time makes the method moresuitable for large scale preparation of immunogenic conjugates, forexample for commercial vaccine production. In addition, the modifiedactivation conditions provide increased yield following conjugation to aprotein (such as a hydrazide-activated protein) than are achieved withthe standard (room temperature) activation conditions. In some examples,the yield of the immunogenic conjugate is about 1.1-fold, about1.2-fold, about 1.3-fold, about 1.4-fold, about 1.5-fold, about1.6-fold, about 1.7-fold, about 1.8-fold, about 1.9-fold, about 2-fold,about 3-fold, about 4-fold, about 5-fold more, or higher when theactivation reaction is carried out at 4° C. than when it is carried outat room temperature. In some examples, the amount of unconjugatedprotein in the reaction is reduced from about 30% when the reaction iscarried out at room temperature, to less than about 5% when the reactionis carried out a 4° C., corresponding to about a 40% increase inconjugation yield

In some examples, the methods also include introducing at least onehydrazide group onto the protein (for example, a carrier protein, suchas a fHbp) by reacting the protein with excess hydrazine,carbohydrazide, hydrazine chloride, or a dihydrazide (for example,succinyl dihydrazide or adipic acid dihydrazide (ADH)) catalyzed by acarbodiimide (such as 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimidehydrochloride (EDC), although any water-soluble carbodiimide can beused). In some examples, the protein is reacted with hydrazine or ADH inthe presence of EDC at about pH 5.5-6.5 (such as pH about 5.5, about5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1, about 6.2,about 6.3, about 6.4, or about 6.5).

In some examples, the hydrazide-activated protein is maintained solubleat a pH of from about 10 to about 11.5, such as from about 10.1, 10.2,10.3, or 10.4 to about 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3,or 11.4, for example about 10.5, with a buffer at a concentration offrom about 3 or less to about 10 mM or more, such as from about 4 or 5mM to about 6, 7, 8, or 9; mM, before conjugation. Suitable buffersinclude but are not limited to Na₂CO₃,3-(cyclohexylamino)-1-propanesulfonicacid (CAPS), and(2-(N-cyclohexylamino)ethane sulfonic acid (CHES). In one example, thehydrazide-activated protein is buffer-exchanged to a solution of aboutpH 10.5 (such as 30 mM NaCl and 3 mM Na₂CO₃, pH 10.5). In otherexamples, the hydrazide-activated protein is maintained soluble atneutral or approximately neutral pH (e.g., pH of about 7 to about 7.5)by activating the protein in the presence of at least one amino acid(such as lysine, arginine, histidine, glycine, serine, threonine,glutamic acid, cysteine, or a mixture of two or more thereof) (see,e.g., WO 07/109129). Amino acids may be included in the activationreaction at a concentration of about 1-500 mM, about 20-300 mM, or about36-144 mM.

The cyanylation conjugation reaction is efficient and reversible,favoring the product formation. In certain embodiments, blocking agentsare employed to remove residual cyanate groups. However, addition of ablocking agent to the reaction mixture drives the conjugation reactionbackward and reduces the conjugation yield by 5-12%. While in certainembodiments it can be desirable to employ blocking agents (for example,ADH, hydrazine, glycine, or ethanolamine) to quench the leftoverresidual cyanate groups, it is generally preferred to avoid their use soas to avoid reduction in conjugate yield. To remove residual cyanategroups in the conjugation product without using a blocking agent, theconjugation time can be prolonged. In some examples, conjugation isconducted at a temperature of from about 0° C. to about 6° C. (forexample, about 2° C., about 2.5° C., about 3° C., about 3.5° C., about4° C., about 4.5° C., about 5° C., about 5.5° C., or about 6° C.) forabout 36 to about 48 hours, for example at about 4° C. for about 36hours, followed by about an additional 18 to 24 hours at a temperatureof from about 20° C. to about 25° C., for example at about 18 hours atabout 20 to 24° C., such that the residual cyanate groups react withwater and decompose. Longer or shorter conjugation times and/or higheror lower conjugation temperatures can be employed, and differentsequences of steps at various times and temperatures can be conducted,as desired. It is desirable, however, to conduct the conjugationreaction, at least initially, at low temperatures, for example fromabout 0° C. to about 6° C., such as about 2° C. to about 6° C. (forexample, about 2° C., about 2.5° C., about 3° C., about 3.5° C., about4° C., about 4.5° C., about 5° C., about 5.5° C., or about 6° C.), so asto reduce the degree of precipitation of the conjugate. In particularexamples, the reaction is carried out at about 4° C.

C. Preparation of Multivalent Immunogenic Conjugates

In some embodiments, the disclosed methods utilize a plurality ofimmunogenic-distinct polysaccharides and/or a plurality of proteins toproduce a multivalent immunogenic conjugate. For example, a mixture oftwo or more (such as 2, 3, 4, 5, or more) immunogenic-distinctpolysaccharides (e.g., a plurality of immunogenic-distinctpolysaccharides) is conjugated to at least one protein (such as fHbp orNspA) using the methods described above. In some examples the pluralityof immunogenic distinct polysaccharides includes two or moremeningococcal polysaccharides (for example, two or more of meningococcalpolysaccharides selected from serotypes A, B, C, W-135, and Y). In oneparticular example, the plurality of immunogenic distinctpolysaccharides includes meningococcal serogroup A polysaccharide(MAPS), meningococcal serogroup C polysaccharide (MCPS), meningococcalserogroup W-135 polysaccharide (MWPS), and meningococcal serogroup Ypolysaccharide (MYPS). In other examples, the plurality ofimmunogenic-distinct polysaccharides includes polysaccharides from twoor more different bacteria (such as two or more of meningococcalpolysaccharides, pneumococcal polysaccharides, Haemophilus influenzaetype b polysaccharide, Vi polysaccharide of Salmonella typhi, and groupB Streptococcus polysaccharides). In one particular example, theplurality of immunogenic-distinct polysaccharides includes at least onemeningococcal polysaccharide, at least one pneumococcal polysaccharide,and at least one Haemophilus influenzae type b polysaccharide.

In some examples, a mixture of more than one polysaccharide (such as aplurality of immunogenic-distinct polysaccharides) can be simultaneouslyactivated by reaction with a single activating agent (or a mixture ofactivating agents) in single batch step. In one example, a mixture ofMAPS, MCPS, MWPS, and MYPS can be reacted with analdehyde-functionalizing agent in a single batch reaction. In anotherexample, a mixture of MAPS, MCPS, MWPS, and MYPS can be reacted withcyanate-functionalizing agent in a single batch reaction. In additionalexamples, a mixture of at least one meningococcal polysaccharide (suchas at least one of meningococcal polysaccharides of serotypes A, B, C,W-135, and Y), at least one pneumococcal polysaccharide (such as atleast one of pneumococcal polysaccharides of serogroups 1, 2, 3, 4, 5,6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F,23F and 33F), and at least one H. influenzae type b polysaccharide canbe activated with an aldehyde-functionalizing agent of acyanate-functionalizing agent. The mixture of activated polysaccharidesis then conjugated to at least one protein (such as fHbp or NspA) in asingle process.

In yet another example, each individual polysaccharide can be activatedby reaction with an activating agent in a separate process. Theseparately activated polysaccharides can then be mixed together prior tothe conjugation step so the activated polysaccharides can besimultaneously conjugated in a single process.

In still further examples, multivalent immunogenic conjugates areprepared by mixing individual immunogenic conjugates. For example, amultivalent immunogenic conjugate can be prepared by mixing conjugatesof MAPS-fHbp, MCPS-fHbp, MWPS-fHbp, and MYPS-fHbp. A multivalentimmunogenic conjugate can also be prepared by mixing one or moreimmunogenic conjugates of a polysaccharide conjugated to fHbp and one ormore immunogenic conjugates of a polysaccharide conjugated to NspA.

The activation and conjugation reactions can be carried out according tothe methods described above.

V. Methods of Eliciting an Immune Response or Inhibiting or TreatingInfection

The conjugates disclosed herein and/or prepared according to the methodsdisclosed herein are administered to a subject in an effective dose (forexample, a therapeutically effective dose) in a suitable form to elicitan immune response in the subject. In some embodiments, the disclosedimmunogenic conjugates are capable of treating, inhibiting, or in someexamples, even preventing infection or disease (for example Neisseriameningitidis infection) in a subject. A subject, as used herein, refersto animals, such as mammals. For example, mammals include humans,primates, dogs, cats, sheep, cattle, goats, pigs, horses, mice, rats,rabbits, guinea pigs, and the like. The terms subject, patient, and hostare used interchangeably. The particular dosage effective to elicit animmune response or to treat, inhibit, or ameliorate an infection dependsupon the age, weight and medical condition of the subject to be treated,as well as on the method of administration. Immunization protocols foruse with the disclosed conjugates provide compositions and methods forpreventing or treating a disease, disorder and/or infection in a subjectare known to one of skill ordinary in the art. Suitable doses andimmunization protocols can be readily determined by those of ordinaryskill in the art.

Pharmaceutical compositions comprising the disclosed conjugates canoffer various advantages over conventional vaccines, including enhancedimmunogenicity of weakly immunogenic antigens, potential reduction inthe amount of antigen used, less frequent booster immunizations,improved efficacy, preferential stimulation of immunity, or potentialtargeting of immune responses. The disclosed immunogenic conjugates,conjugates made by the disclosed methods, and/or pharmaceuticalcompositions including the conjugates can be administered to a subjectby a variety of routes, as discussed below, including but not limited toparenteral, intradermal, transmembranal, transdermal (includingtopical), intramuscular, intraperitoneal, intravenous, intra-arterial,intralesional, subcutaneous, oral, and intranasal (e.g., inhalation)routes of administration. Immunogenic conjugates can be administered bybolus injection or by continuous infusion, as well as by localizedadministration, for example at a site of disease or injury. Theconjugate can be optionally administered in a pharmaceutically orphysiologically acceptable carrier (vehicle).

One or more of the disclosed conjugates (such as 2, 3, 4, 5, 6, or more)can be formulated with adjuvants, diluents, excipients, carriers, andother pharmaceutically acceptable substances. The term “pharmaceuticallyacceptable” is used to refer to a non-toxic material that is compatiblewith a biological system such as a cell, cell culture, tissue, ororganism. In some examples, the disclosed compositions are sterile andcontain either a therapeutically or prophylactically effective amount ofthe conjugate in a unit of weight or volume suitable for administrationto a subject. The pharmaceutically acceptable carriers (vehicles) usefulin this disclosure are conventional. Remington: The Science and Practiceof Pharmacy, The University of the Sciences in Philadelphia, Editor,Lippincott, Williams, & Wilkins, Philadelphia, Pa., 21^(st) Edition(2005), describes compositions and formulations suitable forpharmaceutical delivery of one or more therapeutic compounds ormolecules. The characteristics of the carrier depend on the route ofadministration. Physiologically and pharmaceutically acceptable carriersinclude diluents, fillers, salts, buffers, stabilizers, solubilizers,and other materials which are well known in the art.

Formulation of the immunogenic conjugates into pharmaceuticalcompositions can be accomplished using methods known in the art. In someexamples, the compositions can also contain one or more adjuvants.Suitable adjuvants include, for example, aluminum adjuvants (such asaluminum hydroxide or aluminum phosphate), Freund's Adjuvant, BAY,3(N,N,-dimethylaminoethane)-carbamyl cholesterol (DC-Chol),poly[di(sodium carboxylatephoneoxy)phosphazene] (PCPP), monophosphoryllipid A, CpG, QS-21, cholera toxin, and formyl methionyl peptide. See,e.g., Vaccine Design, the Subunit and Adjuvant Approach, 1995 (M. F.Powell and M. J. Newman, eds., Plenum Press, N.Y.).

The dosage of immunogenic conjugate(s) to be administered to a subjectand the regime of administration can be determined in accordance withstandard techniques well known to those of ordinary skill in thepharmaceutical and veterinary arts, taking into consideration suchfactors as the intended use, particular antigen, the adjuvant (ifpresent), the age, sex, weight, species, general condition, priorillness and/or treatments of the subject, and the route ofadministration. Preliminary doses can be determined according to animaltests, and the scaling of dosages for human administration is performedaccording to art-accepted practices such as standard dosing trials. Forexample, the therapeutically effective dose can be estimated initiallyfrom serum antibody level testing. The dosage depends on the specificactivity of the conjugate and can be readily determined by routineexperimentation.

In practicing immunization protocols for inhibition, treatment, and/orprevention of specified diseases, a therapeutically effective amount ofconjugate is administered to a subject. In some examples, atherapeutically effective amount is the total amount of therapeuticagent (e.g., conjugate) or other active component that is sufficient toshow a meaningful benefit to the subject, such as immune response,treatment, healing, inhibition, prevention, or amelioration of therelevant medical condition (disease, infection, or the like), or anincrease in rate of treatment, healing, prevention or amelioration ofsuch conditions. An effective amount can include the amount of anindividual therapeutic agent (such as an individual immunogenicconjugate disclosed herein), a combination of therapeutic agents (suchas two or more of the disclosed immunogenic conjugates), or acombination of one or more of the disclosed immunogenic conjugates andother agents. A combination can be administered to a subjectsimultaneously, substantially simultaneously, or serially. In particularexamples, a subject is administered an amount of therapeutic agent orcomposition in an amount and for a time to treat, inhibit, or evenprevent an infection, such as an infection with Neisseria meningitidis.

Generally, the amount of conjugate that is an effective amount or atherapeutically effective amount is from about 1 μg/kg or less to about100 μg/kg or more, such as from about 2, 3, 4, 5, 6, 7, 8, 9, 10, 15,20, 25, 30, 35, 40, 45 or 50 μg/kg to about 55, 60, 65, 70, 75, 80, 85,90, or 95 μg/kg body weight. An effective amount can be less if thepost-infection time elapsed is less, since there is less time for thepathogen to proliferate. An effective amount can also depend on thebacterial load at the time of diagnosis. Multiple injectionsadministered over a period of days can be considered for therapeuticusage.

The disclosed immunogenic conjugates can be administered as a singledose or in a series including one or more boosters. For example, asubject can receive a single dose (for example, early in life), then beadministered a booster dose up to 1 month, 2 months, 3 months, 6 months,1 year, 2 years, 3 years, 4 years, 5 years, 6 years, 7 years, 8 years, 9years, 10 years, or more later. More than one booster dose can beadministered if necessary, as determined by one of ordinary skill in theart. The booster dose generates antibodies from primed B-cells, forexample, an anamnestic response. In some examples, the immunogenicconjugate elicits a high primary functional antibody response in infantsor children, and is capable of eliciting an anamnestic responsefollowing a booster administration, demonstrating that the protectiveimmune response elicited by the conjugate vaccine is long-lived.

The disclosed immunogenic conjugates can be formulated into liquidpreparations for example, for oral, nasal, anal, rectal, buccal,vaginal, peroral, intragastric, mucosal, perlingual, alveolar, gingival,olfactory, or respiratory mucosa administration. Suitable forms for suchadministration include suspensions, syrups, and elixirs. The disclosedimmunogenic conjugates can also be formulated for parenteral,subcutaneous, intradermal, intramuscular, intraperitoneal, orintravenous administration, injectable administration, sustained releasefrom implants, or administration by eye drops. Suitable forms for suchadministration include sterile suspensions and emulsions. Suchformulations can be in admixture with a suitable carrier, diluent, orexcipient such as sterile water, physiological saline, glucose, and thelike. The immunogenic conjugates can also be lyophilized. Theimmunogenic conjugates or formulations thereof can contain auxiliarysubstances such as wetting or emulsifying agents, pH buffering agents,gelling or viscosity enhancing additives, preservatives, flavoringagents, colors, and the like, depending upon the route of administrationand the preparation desired. Such preparations can include complexingagents, metal ions, polymeric compounds such as polyacetic acid,polyglycolic acid, hydrogels, dextran, and the like, liposomes,microemulsions, micelles, unilamellar or multilamellar vesicles,erythrocyte ghosts or spheroblasts. Suitable lipids for liposomalformulation include, without limitation, monoglycerides, diglycerides,sulfatides, lysolecithin, phospholipids, saponin, bile acids, and thelike. The presence of such additional components can influence thephysical state, solubility, stability, rate of in vivo release, and rateof in vivo clearance, and are thus chosen according to the intendedapplication, such that the characteristics of the carrier are tailoredto the selected route of administration.

The immunogenic conjugates may be provided as liquid suspensions or asfreeze-dried products. Suitable liquid preparations include, forexample, isotonic aqueous solutions, suspensions, emulsions, or viscouscompositions that are buffered to a selected pH. Transdermalpreparations include lotions, gels, sprays, ointments or other suitabletechniques. If nasal or respiratory (mucosal) administration is desired(e.g., aerosol inhalation or insufflation), compositions can be in aform and dispensed by a squeeze spray dispenser, pump dispenser oraerosol dispenser. Aerosols are usually under pressure by means of ahydrocarbon. Pump dispensers can dispense a metered dose or a dosehaving a particular particle size, as discussed below.

When in the form of solutions, suspensions, or gels, formulations of theconjugate can typically contain a major amount of water (for example,purified water) in addition to the active ingredient. Minor amounts ofother ingredients such as pH adjusters, emulsifiers, dispersing agents,buffering agents, preservatives, wetting agents, gelling agents, colors,and the like can also be present.

In specific examples, the compositions are isotonic with the blood orother body fluid of the subject. The isotonicity of the compositions canbe attained using sodium tartrate, propylene glycol, or other inorganicor organic solutes. Sodium chloride is particularly preferred. Bufferingagents can be employed, such as acetic acid and salts, citric acid andsalts, boric acid and salts, and phosphoric acid and salts. Parenteralvehicles include sodium chloride solution, Ringer's dextrose, dextroseand sodium chloride, lactated Ringer's or fixed oils. Intravenousvehicles include fluid and nutrient replenishers, electrolytereplenishers (such as those based on Ringer's dextrose), and the like.

Viscosity of the compositions can be maintained at the selected levelusing a pharmaceutically acceptable thickening agent. One suitablethickening agent is methylcellulose, because it is readily andeconomically available and is easy to work with. Other suitablethickening agents include, for example, xanthan gum, carboxymethylcellulose, hydroxypropyl cellulose, carbomer, and the like. Theconcentration of the thickener can depend upon the agent selected and isused in an amount that can achieve the selected viscosity. Viscouscompositions are normally prepared from solutions by the addition ofsuch thickening agents.

A pharmaceutically acceptable preservative can be employed to increasethe shelf life of the compositions. Benzyl alcohol can be suitable,although a variety of preservatives including, for example, parabens,thimerosal, chlorobutanol, or benzalkonium chloride can also beemployed. A suitable concentration of the preservative can be from 0.02%to 2% based on the total weight although there can be appreciablevariation depending upon the agent selected.

Pulmonary delivery of the conjugate can also be employed. The conjugateis delivered to the lungs of a mammal while inhaling and traversesacross the lung epithelial lining to the blood stream. A wide range ofmechanical devices designed for pulmonary delivery of therapeuticproducts can be employed, including but not limited to nebulizers,metered dose inhalers, and powder inhalers, all of which are familiar tothose of ordinary skill in the art. These devices employ formulationssuitable for the dispensing of the conjugate. Typically, eachformulation is specific to the type of device employed and can involvethe use of an appropriate propellant material, in addition to diluents,adjuvants, and/or carriers useful in therapy.

The conjugate is advantageously prepared for pulmonary delivery inparticulate form with an average particle size of from 0.1 μm or less to10 μm or more, more such as from about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, or 0.9 μm to about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0,5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, or 9.5 μm for pulmonarydelivery. Pharmaceutically acceptable carriers for pulmonary delivery ofthe conjugates include carbohydrates such as trehalose, mannitol,xylitol, sucrose, lactose, and sorbitol. Other ingredients for use inpulmonary formulations can include dipalmitoylphosphatidylcholine(DPPC), dioleoyl phosphatidylethanolamine (DOPE), distearoylphosphatidylcholine (DSPC), and dioleoyl phosphatidylcholine (DOPC).Natural or synthetic surfactants can be used, including polyethyleneglycol and dextrans, such as cyclodextran. Bile salts and other relatedenhancers, as well as cellulose and cellulose derivatives, and aminoacids can also be used. Liposomes, microcapsules, microspheres,inclusion complexes, and other types of carriers can also be employed.

Formulations suitable for use with a nebulizer, either jet orultrasonic, typically comprise the conjugate dissolved or suspended inwater at a concentration of about 0.01 mg or less to 100 mg or more ofconjugate per mL of solution, such as from about 0.1, 1, 2, 3, 4, 5, 6,7, 8, 9, or 10 mg to about 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, or 90 mg of conjugate per mL of solution. Theformulation can also include a buffer and a simple sugar (for example,for protein stabilization and regulation of osmotic pressure). Thenebulizer formulation can also contain a surfactant, to reduce orprevent surface induced aggregation of the conjugate caused byatomization of the solution in forming the aerosol.

Formulations for use with a metered-dose inhaler device generallycomprise a finely divided powder containing the inventive compoundsuspended in a propellant with the aid of a surfactant. The propellantcan include conventional propellants, such as a chlorofluorocarbon, ahydrochlorofluorocarbon, hydrofluorocarbons, and hydrocarbons, such astrichlorofluoromethane, dichlorodifluoroethane,dichlorotetrafluoroethanol, and 1,1,1,2-tetrafluoroethane, andcombinations thereof. Suitable surfactants include sorbitan trioleate,soya lecithin, and oleic acid.

Formulations for dispensing from a powder inhaler device typicallycomprise a finely divided dry powder containing the conjugate,optionally including a bulking agent, such as lactose, sorbitol,sucrose, mannitol, trehalose, or xylitol in an amount that facilitatesdispersal of the powder from the device, typically from about 1 wt. % orless to 99 wt. % or more of the formulation, such as from about 5, 10,15, 20, 25, 30, 35, 40, 45, or 50 wt. % to about 55, 60, 65, 70, 75, 80,85, or 90 wt. % of the formulation.

When the conjugate is administered by intravenous, cutaneous,subcutaneous, or other injection, the composition can be in the form ofa pyrogen-free, parenterally acceptable aqueous solution. Thepreparation of parenterally acceptable solutions with suitable pH,isotonicity, stability, and the like, is within the ordinary skill inthe art. In one example, a pharmaceutical composition for injectioncontains an isotonic vehicle such as Sodium Chloride Injection, Ringer'sInjection, Dextrose Injection, Dextrose and Sodium Chloride Injection,Lactated Ringer's Injection, or other vehicles as are known in the art.The pharmaceutical compositions can also contain stabilizers,preservatives, buffers, antioxidants, or other additives known to thoseof ordinary skill in the art.

The duration of the injection can vary depending upon various factors,and can comprise a single injection administered over the course of afew seconds or less, to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours or more of continuousintravenous administration.

The conjugate can be administered topically, systematically, or locally,via a liquid or gel, or as an implant or device.

The disclosed conjugates or the disclosed conjugation methods can beuseful in preparing vaccines for the treatment, inhibition, orprevention of a variety of bacterial infections, including but notlimited to infections by Neisseria meningitidis, Neisseria gonorrhoeae,Streptococcus pneumoniae, Streptococcus pyogenes (Group AStreptococcus), Streptococcus agalaciae (Group B Streptococcus),Streptococcus (viridans group), Streptococcus faecalis, Streptococcusbovis, Streptococcus (anaerobic sps.), Streptococcus pneumoniae,Haemophilus influenzae, and Salmonella typhi.

The conjugates can be administered in combination with various vaccineseither currently being used or in development, whether intended forhuman or non-human subjects. Examples of vaccines for human subjects anddirected to infectious diseases include combined diphtheria and tetanustoxoids vaccine; pertussis whole cell vaccine; inactivated influenzavaccine; 23-valent pneumococcal vaccine; live measles vaccine; livemumps vaccine; live rubella vaccine; Bacille Calmette-Guerin I (BCG)tuberculosis vaccine; hepatitis A vaccine; hepatitis B vaccine;hepatitis C vaccine; rabies vaccine (e.g., human diploid cell vaccine);inactivated polio vaccine; meningococcal polysaccharide vaccine (e.g.,Menomune®, Sanofi Pasteur); quadrivalent meningococcal conjugate vaccine(e.g., Menactra® (Sanofi Pasteur) or Menveo® (Novartis)); yellow feverlive virus vaccine; typhoid killed whole cell vaccine; cholera vaccine;Japanese B encephalitis killed virus vaccine; adenovirus vaccine;cytomegalovirus vaccine; rotavirus vaccine; varicella vaccine; anthraxvaccine; small pox vaccine; and other commercially available andexperimental vaccines.

The conjugates can be provided to an administering physician or otherhealth care professional in the form of a kit. The kit is a packagewhich houses a container which contains the immunogenic conjugate andinstructions for administering the composition to a subject. The kit canoptionally also contain one or more other therapeutic agents. The kitcan optionally contain one or more diagnostic tools and instructions foruse. For example, a composition containing two or more of the disclosedimmunogenic conjugates or other vaccines can be included, or separatepharmaceutical compositions containing different conjugates, vaccines,or therapeutic agents. The kit can also contain separate doses of theimmunogenic conjugate for serial or sequential administration. The kitcan contain suitable delivery devices, e.g., syringes, inhalationdevices, and the like, along with instructions for administrating thetherapeutic agents. The kit can optionally contain instructions forstorage, reconstitution (if applicable), and administration of any orall therapeutic agents included. The kits can include a plurality ofcontainers reflecting the number of administrations to be given to asubject. If the kit contains a first and second container, then aplurality of these can be present.

The disclosure is illustrated by the following non-limiting Examples.

Example 1 Preparation of Conjugates

Methods

MAPS was produced by SynCo BioPartners, Amsterdam, The Netherlands. MCPSwas from FioCruz, BioMaguinhus, Brazil. MWPS and MYPS were from Chiron(Emoryville, Calif.). Tetanus toxoid (TT) was obtained from WyethVaccines and Serum Institute of India. 1-cyano-4-dimethylaminopyridiniumtetrafluoroborate (CDAP) was purchased from Sigma-Aldrich (St. Louis,Mo.).

The gene of fHbp1 was amplified by PCR using genomic N. meningitidisH44/76 genomic DNA as a template and forward primerAAGCTTCCTCGAGTGAGCAGTGGAGGGGGTGGTGTCGCC (SEQ ID NO: 9) and reverseprimer GGCGGGGAATTCACTTATTGCTTGGCGGCAAGGCCGAT (SEQ ID NO: 10). The geneof fHbp2 was amplified by PCR using genomic N. meningitidis 7608 genomicDNA as a template and forward primerAAGCTTCCTCGAGTGAGCAGTGGAGGCGGCGGTGTCGCC (SEQ ID NO: 11) and reverseprimer GGCGGGGAATTCACTTACTACTGTTTGCCGGCGATGCC (SEQ ID NO: 12). The PCRproducts were cloned in the XhoI-EcoRI site of pT7-MAT-Tag-Flag-1 vector(Sigma-Aldrich) which were then used to transform E. coli cellsBL21(DE3). The transformed cells were grown in LB broth, induced with 1mM IPTG, the cells were lysed, and the His-tagged proteins purified onNi columns.

For the fHbp1/fHbp2 fusion protein (fHbp1+2), first the gene of fHbp1was amplified by PCR using genomic N. meningitidis H44/76 genomic DNA asa template and the forward primer used for fHbp1 (SEQ ID NO: 9) and thereverse primerCGATCCGCCACCGCCAGAGCCACCTCCGCCTGAACCGCCTCCACCTTGCTTGGCAAGG CCGAT (SEQ IDNO: 13). PCR product was reamplified using the same forward primer andthe reverse primer GCCGCCTCCTCTAGAACCGCCACCGCCAGAGCCACC (SEQ ID NO: 14).The gene of fHbp2 was amplified by PCR using genomic N. meningitidis7608 genomic DNA as a template and the forward primerGGTGGAGGCGGTTCAGGCGGAGGTGGCTCTGGCGGTGGCGGATCGGGAGGCGGCGGT GTCGCC (SEQ IDNO: 15) and the reverse primer used for fHbp2 (SEQ ID NO: 12). The PCRproduct was reamplified using the forward primerGGTGGCGGTTCTAGAGGAGGCGGCGGTGTCGCC (SEQ ID NO: 16) and the same reverseprimer. The fHbp1 PCR product was digested with XhoI and XbaI, while thefHbp2 PCR product was digested with XbaI and EcoRI. The digestedproducts were cloned into the XhoI-EcoRI site of pT7-MATTag-Flag-1vector (Sigma-Aldrich) which was then used to transform E. coli cellsBL21(DE3). The transformed cells were grown in LB broth, induced with 1mM IPTG, the cells were lysed and the His-tagged proteins purified on Nicolumns.

The purified proteins were analyzed on 10% SDS-PAGE gels and Westernblots using the Jar 5 and Jar 11 monoclonal antibodies.

Conjugation of polysaccharide to fHbp was carried out using CDAPconjugation method of Lees et al (Vaccine 26:190-198, 1996) withmodification which involved carrying out the entire activation andconjugation reactions at 4° C. First, 10 μL PS (10 mg/mL; Mn A, C, W135or Y) was mixed with 1 μL CDAP (100 mg/mL in acetonitrile), and then 1μL triethylamine (TEA, 0.2 M) was added to the reaction mixture. After1.5-2 hours incubation at 4° C., 4 μL of 0.1 M phosphate buffer, pH 5.5was added to the reaction mixture followed by addition of 0.1 mg fHbp orhydrazide-modified TT prepared according to Lee et al. (Vaccine27:726-732, 2009). The conjugation reaction proceeded overnight in acold room with mixing by a rotary mixer. After dialysis against 10 mMHEPES, pH 7.2, 50 mM NaCl (4×1000 mL) at 4° C., the conjugation productwas adjusted to [PS]=0.2 mg/mL with dialysis buffer and stored inrefrigerator.

Samples of proteins, polysaccharides, and conjugate products (25 μL, 0.1mg/mL) were applied to a Waters Ultrahydrogel™ 2000 column with 0.9%NaCl, 10 mM Tris (pH 7.2), 1 mM EDTA, at 0.5 mL/minute in a Dionex HPLCsystem using Chromelean® software with a UV detector at 280 nm formonitoring protein signal, and a refractive index detector for detectingprotein, polysaccharide and conjugate.

Results

The SDS-PAGE gels and Western blots of the purified fHbp1, fHbp2 andfHbp(1+2) proteins used for the production of the conjugate vaccine areshown in FIGS. 1A-B. The purified fHbp (1+2) protein was conjugated toPS either by the conventional CDAP conjugation method developed by Leesat al. (Vaccine 26:190-198, 1996) which required 2-2.5 minutesactivation time of PS at room temperature in order to achieve maximalyield or by the modified method where activation of PS with CDAP wasperformed at 4° C. for 1.5 to 2 hours. Size exclusion HPLC profiles ofthe products of the two methods showed that the modified method resultedin higher conjugation yield when compared to the conventional method(FIG. 2).

The modified conjugation method was used for the subsequent conjugationof all the purified fHbp proteins to meningococcal polysaccharides. Thesize-exclusion HPLC profiles of fHbp1 and MCPS-fHbp1, MCPS-fHbp2 andMCPS-fHbp(1+2) conjugates, monitored at 280 nm, are shown in FIG. 3A,and those of fHbp(1+2) and its conjugates to MAPS, MCPS, MWPS and MYPSare shown in FIG. 3B. The peak of each of the fHbp1, fHbp2 and fHbp(1+2)is at 22-23 minutes. Conjugate formation between PS and the proteins isindicated by the shift of protein signal from 22-23 minute to highermolecular weight position at 15-19 minutes upon conjugation, withremaining leftover unconjugated protein residue unmoved.

Example 2 Immunogenicity of fHbp Conjugates

Methods

Groups of 5 or 10 NIH-Swiss mice were immunized subcutaneously with 0.1mL inoculum containing conjugates prepared in Example 1 or mixture offHbp and native PS (control) on days 0 and 14, and 28 with seracollected on day 35.

IMMUNLON® 1B plates (Dynatech) were coated with 100 μL of coatingsolution containing PBS, pH 7.4, native Mn A, C, W135 or Y PS (5 μg/mL)admixed with methylated human serum albumin (5 μg/mL), or 1 μg/mL fHbp1or fHbp2 for two hours, and washed three times with 150 μL of washingbuffer (PBS, pH 7.4, 0.05% TWEEN® 20 and 0.02% NaN₃). Serum samples orreference serum (assigned with 3,200 units/mL anti-Mn A, C, W135 or Y PSantibody, or 32,000 units/mL for anti-fHbp1 or fHbp2) were diluted withdilution buffer (PBS, pH 7.4, 4% newborn calf serum, 0.02% NaN₃) in aseries of two-fold dilutions starting from 1:200. One hundred μL ofthese diluted specimens were applied to each well of the ELISA plates.Plates were incubated overnight at room temperature, washed three timeswith 150 μL washing buffer, and then incubated with 100 μL goatanti-mouse IgG Fc conjugated with alkaline phosphatase ( 1/3000 dilutionin dilution buffer) for two hours. The plates were washed three timeswith 150 μL washing buffer and incubated with 100 μL p-nitrophenylphosphate (1 mg/mL in 1 M Tris, pH 9 plus 0.3 mM MgCl₂) to developcolor. Fifty μL of 1 N NaOH was added to stop the reaction and theabsorbance was measured with an ELISA plate reader (Model EL800,Bio-Tek, Winooski, Vt.) at 405 nm. The antibody levels of the sampleswere calculated from the readings based on the standard curve of thereference serum co-assayed in the same plate. The geometric mean ofantibody level for each mouse group was calculated.

Results

Mice immunized with MCPS conjugates to fHbp1, fHbp2 and fHbp(1+2)mounted a strong IgG response to both the carrier proteins fHbp1, fHbp2and fHbp(1+2) and also the meningococcal C polysaccharide (Table 1). Asexpected, an immune response to the meningococcal C polysaccharide wasnot observed when the mice were immunized with the unconjugated mixtureof proteins (fHbp1, fHbp2 and fHbp(1+2)) and meningococcal Cpolysaccharide. This suggests that fHbp1, fHbp2 and fHbp(1+2) can serveas effective carrier proteins enhancing the immunogenicity of theconjugated MCPS. Furthermore, the proteins in fHbp1MCPS, fHbp2MCPS andfHbp(1+2)MCPS conjugates could induce comparable antibody levels(units/mL) as the unconjugated protein in the control groups. Since thefusion protein fHbp(1+2) was capable of inducing a strong immuneresponse to both fHbp1 and fHbp2, it was used as the carrier protein forsubsequent experiments.

TABLE 1 Geometric mean ELISA IgG [Ab] level (units/mL)^(a) in antiserafrom mice (n = 5) one week after immunizations of 1 μg conjugate or 1 μgprotein plus 1 μg MCPS mixture (control) Antigens Immunogen MCPS fHbp1fHbp2 fHbp1 + MCPS control 518 7558 fHbp1MCPS conjugate 17,332 242,257fHbp2 + MCPS control 692 46,061 fHbp2MCPS conjugate 11,648 47,553fHbp(1 + 2)MCPS conjugate 16,565 175,413 47,302 ^(a)Assigned IgG [Ab]levels (units/mL) for reference sera: [anti-MCPS] = 3200; [anti-fHbp1] =32,000; [anti-fHbp2] = 32,000

The geometric mean ELISA IgG levels against MAPS, MCPS, MWPS, MYPS,fHbp1 and fHbp2 induced by the conjugates in singular monovalent orcombined formulations are shown in Table 2. Each conjugate induced muchhigher anti-PS IgG antibody compared to the control group injected withmixture of fHbp(1+2) and meningococcal groups A, C, W135 and Y PS(13,803-106,193 units/mL vs. 21-774 units/mL). The level of antibodyagainst the carrier protein induced in mice immunized with the conjugatewas similar to the level of antibody induced in mice immunized with theunconjugated carrier fHbp (1+2) protein (23,195-98,252 units/mL vs.64,468 units/mL for fHbp1 component; and 10,611-35,327 units/mL vs.6,393 units/mL for fHbp2 component). For the combined formulation, infull or one quarter dosage, similar levels of antibody were inducedagainst respective PS antigens and carrier protein components comparedto each singular conjugate component. Together, these data demonstratethat fHbp(1+2) can serve as an effective carrier protein for conjugatesof meningococcal groups A, C, W135 and Y PS in singular monovalent orcombined formulations.

TABLE 2 Geometric mean ELISA [IgG] level (units/mL)^(a) in antisera frommice (n = 10) one week after immunizations of 1 μg fHbp(1 + 2) plusmixture (ACWY PS) of 1 μg each of MAPS, MCPS, MWPS, and MYPS (Group a),1 μg each conjugate (Groups b-e), combined formulation (Group f), or ¼amount of the combined formulation (Group g) Antigens Group ImmunogenMAPS MCPS MWPS MYPS fHbp1 fHbp2 a fHbp(1 + 2) + 387 774 21 79 64,4686393 ACWY PS b fHbp(1 + 2)MAPS 166,193 23,195 11,330 conj. c fHbp(1 +2)MCPS 52,448 98,252 35,327 conj. d fHbp(1 + 2)MWPS 13,803 28,109 10,611conj. e fHbp(1 + 2)MYPS 71,986 45,535 15,412 conj. f (b + c + d + e)29,760 12,829 8831 32,219 28,823 10,229 g (b + c + d + e) × ¼ 33,2149870 9638 31,214 30,930 9075 ^(a)Assigned IgG [Ab] levels (units/mL) forreference sera: [anti-MAPS] = 3200; [anti-MCPS] = 3200; [anti-MWPS] =32,000; [anti-MYPS = 32,000]; [anti-fHbp1] = 32,000; [anti-fHbp2] =32,000

Example 3 Bactericidal Activity of Induced Antisera

Methods

The serum bactericidal assay was performed as previously described(Moran et al., Infect. Immun. 62:5290-295, 1994) using normal humanserum pre-screened for lack of bactericidal activity against the teststrain as a source of complement. Individual mouse sera from each groupof mice were pooled before being tested in the serum bactericidal assay.Depending on the amount of serum available and the expected titer, thepooled mouse sera were tested using a starting dilution of 1:2 to 1:8.When starting dilutions of 1:4 or 1:8 were used, results wereextrapolated to lower dilutions using a typical killing curve. Thereciprocal of the highest dilution of serum that killed >50% of thebacteria was taken as the end point titer of the serum. If the percentkill was between 35% and 50% at the lowest dilution tested, the serumwas assigned the titer of the next lower dilution. If the percent killwas between 0% and 35% the serum was assigned a titer two dilutionslower. If there was less than 50% killing at a dilution of 1:2, theserum was assigned a titer of 1:1. The highest dilution tested was1:512. All the pre-vaccination sera from the mice lacked bactericidalantibodies against any of the test strains and were assigned a titer of1:1.

Results

The bactericidal activity of the induced IgG antibody against fHbp(1+2)was tested against N. meningitidis serogroup B fHbp1-expressing strains44/76 and 8570, and fHbp2-expressing strains 7608 and 8047, andserogroup X strains 9557, 9558, and 9559 shown in Table 3. The pre-bleedcontrol group showed little bactericidal activity, and its titer wasassigned with 1. Bactericidal antibodies to fHbp1-expressing serogroup Band X N. meningitidis strains were observed in the sera of miceimmunized with the unconjugated mixture of fHbp(1+2) and serogroups A,C, W-135, and Y PS. While antibodies to fHbp2 were observed in theinduced antisera, they were not found to be bactericidal. Bactericidalantibodies to fHbp1-expressing serogroup B and X N. meningitidis strainswere also observed in the sera of mice immunized with fHbp(1+2) andserogroups A, C, W-135, and Y PS conjugates. Bactericidal antibodies tofHbp2 was variable in the sera of mice immunized with the conjugate, andin general the bactericidal antibodies to fHbp1 immunized withfHbp(1+2)MWPS conjugate was comparatively lower than the levels presentin sera of mice immunized with the other fHbp(1+2) PS conjugates. In thecombined formulation, the full dosage group (group f) had about the samebactericidal titer (titer 4) as the control group for serogroup BfHbp1-expressing strains and a reduced titer (titer 2) for serogroup Xstrains, while the ¼ dosage group had reduced titer (titer 2) for bothgroups B and X strains.

TABLE 3 Bactericidal titers against groups B and X meningococci (MB andMX, respectively) of pooled antisera from mice (n = 10; groups a-g) oneweek after immunizations of 1 μg fHbp(1 + 2) plus mixture (ACWY PS) of 1μg each of MAPS, MCPS, MWPS, and MYPS (group a), 1 μg each conjugate(groups b-e), combined formulation (group f), or ¼ amount of thecombined formulation (group g) MB Strains fHbp1 fHbp2 MX Strains GroupImmunogen 44/76 8570 7608 8047 9557 9558 9559 Pre-bleed pool 1 1 1 1 1 1a fHbp(1 + 2) + 2 4 1 1 4 4 4 ACWY PS b fHbp(1 + 2) MAPS 4 4 2 2 4 8 4conj. c fHbp(1 + 2) MCPS 4 4 1 1 4 4 4 conj. d fHbp(1 + 2) MWPS 2 2 1 22 1 2 conj. e fHbp(1 + 2) MYPS 2 4 2 1 4 4 4 conj. f (b + c + d + e) 4 41 1 2 1 2 g (b + c + d + e) × ¼ 2 2 1 1 2 2 2

The bactericidal activity of the PS-specific IgG antibody was measuredby bactericidal assay against PS-homologous strains (4 strains forserogroups A and C and 3 strains for W-135 and Y) (Table 4). Thepre-bleed and the mixture of ACWY PS and fHbp(1+2) control groups showedno bactericidal activity (titer 1). All the tested antisera induced bymonovalent conjugates or combined formulations were found to bebactericidal to the tested PS-homologous strains (Table 4). Since thecapsular polysaccharides from serogroups A, C, W-135 and Y are known tobe non-immunogenic in mice, these data suggest that fHbp can indeed beused as a carrier protein for a conjugate vaccine which in turn wouldinduce PS-specific IgG antibody. Comparing the bactericidal titer of theantisera induced by monovalent conjugates with that induced by thecombined formulation at full as well as ¼ reduced dosage, serogroups A,C and Y monovalent conjugates induced antisera with equal or highertiter than the combined formulations. On the contrary, serogroup W-135monovalent conjugate induced antisera with equal or lower titer than thecombined formulations.

TABLE 4 Bactericidal titers against PS-homologous A, C, W-135, and Ystrains of pooled antisera from mice (n = 10; groups a-g) one week afterimmunizations of 1 μg fHbp(1 + 2) plus mixture (ACWY PS) of 1 μg each ofMAPS, MCPS, MWPS, and MYPS (group a), 1 μg each conjugate (groups b-e),combined formulation (group f), or ¼ amount of the combined formulation(group g) MA Strains Group Immunogens 5878 7891 8822 8991 b fHbp(1 +2)MAPS conj 16 256 32 16 f (b + c + d + e) 8 256 16 8 g (b + c + d + e)× ¼ 8 256 8 8 MC Strains 5416 5660 8241 8837 c fHbp(1 + 2)MCPS conj. 168 32 16 f (b + c + d + e) 2 2 8 4 g (b + c + d + e) × ¼ 4 2 8 4 MWStrains 6309 7510 8122 d fHbp(1 + 2)MWPS conj. 64 8 32 f (b + c + d + e)128 8 128 g (b + c + d + e) × ¼ 64 16 128 MY Strains 4463 6972 8020 efHbp(1 + 2)MYPS conj. 4 16 8 f (b + c + d + e) 4 8 4 g (b + c + d + e) ×¼ 4 8 8

In view of the many possible embodiments to which the principles of thedisclosure may be applied, it should be recognized that the illustratedembodiments are only examples and should not be taken as limiting thescope of the invention. Rather, the scope of the invention is defined bythe following claims. We therefore claim as our invention all that comeswithin the scope and spirit of these claims.

We claim:
 1. A pharmaceutical composition comprising: an immunogenicconjugate comprising a Meningococcal group A polysaccharide conjugatedto an fHbp fusion protein comprising the amino acid sequenceSEQ.ID.NO:8; an immunogenic conjugate comprising a Meningococcal group Cpolysaccharide conjugated to an fHbp fusion protein comprising the aminoacid sequence SEQ.ID.NO:8; an immunogenic conjugate comprising aMeningococcal group W polysaccharide conjugated to an fHbp fusionprotein comprising the amino acid sequence SEQ.ID.NO:8; and animmunogenic conjugate comprising a Meningococcal group Y polysaccharideconjugated to an fHbp fusion protein comprising the amino acid sequenceSEQ.ID.NO:8.
 2. The pharmaceutical composition comprising one or moreimmunogenic conjugates of claim 1 and a pharmaceutically acceptablecarrier.
 3. The pharmaceutical composition of claim 2, furthercomprising an adjuvant.
 4. A method of eliciting an immune response toNeisseria meningitidis in a subject, comprising administering aneffective amount of the pharmaceutical composition of claim 1 to thesubject, thereby eliciting an immune response to Neisseria meningitidisin the subject.
 5. The method of eliciting an immune response toNeisseria meningitidis in a subject, comprising administering aneffective amount of the pharmaceutical composition of claim 2 to thesubject, thereby eliciting an immune response to Neisseria meningitidisin the subject.
 6. The method of eliciting an immune response toNeisseria meningitidis in a subject, comprising administering aneffective amount of the pharmaceutical composition of claim 3 to thesubject, thereby eliciting an immune response to Neisseria meningitidisin the subject.